Hitherto, both of a fluorocompound and a silicone compound have been used as a mold release agent for molding various rubbers and resins. For example, as the silicone compound, known are straight silicone oils, various modified silicone oils, silicone resins and the like, and as the fluorocompound, known are perfluoroalkyl group-containing phosphate ester compounds and the like. Further, the silicone compound and the fluorocompound can be mixed to improve the mold releasability (cf. Patent Document 1 and Patent Document 2).
Conventionally used fluorocompounds mainly were a compound having 8 or more carbon atoms in the fluoroalkyl chain. Recently concern that fluorocompounds having at least 8 carbon atoms in the perfluoroalkyl chain are environmentally persistent due to difficult decomposition and high accumulation. Therefore, a fluorocompound having a short fluoroalkyl chain which has low environmental persistence is sought.
A fluorosilicone compound having both of a silicone moiety and a fluorine moiety in the molecule is also known. Patent Document 3 describes a fluorosilicone compound which is one component in a composition forming a curable silicone film exhibiting water- and oil-repellency, but Patent Document 3 does not describe the use of the fluorosilicone compound alone or the mold releasability.
Patent Document 4 describes that a fluorosilicone oil having a different structure has mold releasability, but the fluorosilicone oil has the problem that the performances thereof are not sufficient.                Patent Document 1: JP-A-52-39587        Patent Document 2: JP-A-52-42550        Patent Document 3: JP-A-08-319424        Patent Document 4: JP-A-2000-26608        